This year, 56 students in a class have subscribed to "junior high school students' Mathematics Learning". In the first half of this year, 25 boys and 15 girls have subscribed to the magazine. In the second half of this year, 26 boys and 25 girls have subscribed to the magazine, and 23 boys have subscribed to the magazine all year round. So the number of girls who have subscribed to the magazine only in the first half of this year is 25______ Name

This year, 56 students in a class have subscribed to "junior high school students' Mathematics Learning". In the first half of this year, 25 boys and 15 girls have subscribed to the magazine. In the second half of this year, 26 boys and 25 girls have subscribed to the magazine, and 23 boys have subscribed to the magazine all year round. So the number of girls who have subscribed to the magazine only in the first half of this year is 25______ Name

∵ there are 23 boys subscribing to magazines throughout the year. There are 2 boys subscribing to magazines in the first half of the year and 3 boys subscribing to magazines in the second half of the year. There are 23 + 2 + 3 = 28 boys subscribing to magazines in the whole year. Then there are 56-28 girls subscribing to magazines in the whole year. Suppose there are x girls subscribing to magazines in the whole year. (15-x) + (25-x) + x = 28. The equation is: x = 12, ∵ 15-12 = 3. A: there are 3 girls subscribing to magazines in the first half of the year So the answer is: 3

There are two warehouses. The original tonnage of grain stored in warehouse A is 5 / 7 of that of warehouse B. If 6 tons are transferred from warehouse B to warehouse A, the tonnage of warehouse A is 4 / 5 of that of warehouse B. how many tons are there in warehouse A and warehouse B?
fast

Suppose that a was originally x tons and B was originally y tons. According to "the tonnage of grain stored in a warehouse was 5 / 7 of B", we get x = 5 / 7Y. According to "if B transfers 6 tons to a, the tonnage of a is 4 / 5 of B", we get x + 6 = 4 / 5 (y-6) x = 5 / 7yx + 6 = 4 / 5 (y-6) 5 / 7Y + 6 = 4 / 5 (y-6) 5 / 7y-4 / 5Y = - 24 / 5-625 / 35y-28 / 3

By the quadratic equation of one variable x ^ 2-7x + 6 = 0 2x ^ 2 + x-3 = 0

(x-1)(x-6)=0
x1=1
x2=6
(x-1)(2x+3)=0
x1=1
x2=-3/2

Simple operation of 67 * 76 + 76 * 33

67*76+76*33
=76×（67+33）
=76×100
=7600

Given that the sequence {an} is an equal ratio sequence with the first term of 1, Sn is the sum of the first n terms of {an}, and 9s3 = S6, then the sum of the first 5 terms of {an} is ()
A. 30B. 31C. 29D. 32

According to the meaning of the title, the common ratio Q ≠ 1, ｜ 9 · 1 − Q31 − q = 1 − q61 − Q, that is, q6-9q3 + 8 = 0, the solution is: q = 2 or q = 1 (rounding off), ｜ S5 = 1 − 251 − 2 = 31, so B

36 times 34 out of 35

=（35+1）*（34/35）
=35*（34/35）+34/35
=34+34/35
=34 and 34 / 35

For rational numbers a and B, the meaning of the new operation * is: a * b = a * B + A + B, to find the solution of the equation (half x) * 3 = 4
Note: * is a symbol and * is a multiplication

(half x) * 3 = 0.5x * 3 + 0.5x + 3 = 2x + 3 = 4
We get 2x = 1, x = 0.5

What's the probability that any one of the three digits out of the five digits of 12345 without repetition is even

C(2,1)×P(4,2)÷P(5,3)
=2×4×3÷﹙5×4×3﹚
=2／5

What is the difference between matrix similarity and matrix contract

The essential difference is that the matrix is similar if the block is invariable
Matrix contract, keep the sign of eigenvalue (i.e. sign) unchanged

240 divided by two digit quotient is one digit, there are several possibilities kkkkkk

4 possible